Commutator-bar.



No. 745,336. PATENTED DEC. l, 1903. W. L. R. EMMET.

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UNITED STATES Patented December 1, 1903.

PATENT OEEICE.

WILLIAM L. R. EMMET, OF SCIIENECTADY, NEW YORK, ASSIGNOR TO GEN- ERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONI Nl UTATOR-BAR.

SPECIFICATION forming part of Letters Patent No. 745,336, dated Decemberl, 1903- Application led May l0, 1900. serial No, 16,155. (No model.)

To a/ZZ whom, it may concern.:

Be it known that I, WILLIAM LE R. EMMET, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Commutator-Bars, ot'which the following is a specification.

The object of this invention is to prevent relative motion ofcommutator-bars and an uneven surface or tread ot' the brushes resultingtherefrom.

In carrying out the invention I provide the com mutator-bar on itslateral faces which abut against the faces of the adjacent bars with arougheued, knurled, pitted, or indented surface, which under thepressure of the bars in assembling bites into the insulating materialand locks the several bars into a compact whole, preventing under thecentrifugal and other strains to which the bars are subjected anyrelative radial motion. I prefer to form this roughened surface byrunning the bar between rollers having suitable projections on thesurfaces which produce the desired indentations, the excess of metaldisplaced in producing the pits or indentations being distributed andflattened 0E, if desired, to correct dimensions by a final shapingprocess, preferably by drawing the bar through a die. It is, however,not essential to produce the roughnesses by rollers, as irregularitiesin the lateral faces may be produced by pressing, scoring, or otherwiseindenting them. I prefer to use an adhesive varnish between the surfacesof the bars and of the insulating material. This varnish after havingbeen hardened by baking glues the insulation securely to the bars, andthus tends to prevent relative motion of the bars or insulation-pieces.Where the bars are scored or indented, the depressions are lled by thevarnish, and thus the strength of the bond between the bars and thevarnish is increased. The expansion of the parts under heat or pressurealso tends to make theinsulating material expand into the depressions,and thus forms a bond which prevents relative motion.

The novel features of my invention will be more specifically pointed outhereinafter and will be definitely indicated in the claims appended tothis specification.

In the accompanying drawings, which illustrate the invention, Figure 1is a side elevation of a commutator-bar embodying my iniprovements.Figs. 2 and 3 are similar Views of niodied plans of roughening thelateral faces; and Figs. 4f, 5, and 6 represent assembled a plurality ofcommutator-bars such as indicated in Figs. 3, 2, and l, respectively,the rugosities in all of the figures being exaggerated for the purposeof betterillustrating the invention, Fig. 4t being a section on line c cof Fig. 3, and Fig. 6 a section on line a a of Fig. l.

The coinmutator-bar shown in the drawings is one of special type; but myinvention is not limited to any particular form.

The essential feature of my invention is in providing the faces withroughnesses, which prevent one bar from slipping on its neighbor.

The form shown in Fig. 1 is provided with a plurality of rectangularpits, as indicated at l l, dac., which should for the best result bedistributed over the bulk ot' the sides of the bar. The bars may beroughly shaped by casting or otherwise, and they may be upset cold in adie, which brings them to accurate prismatic dimensions withoutmachining and which may also serve to correct their form in otherrespects. As hereinbefore stated, accuracy of dimension is onlyimperative in respect of the elevated surfaces, which being relativelysmall in area are easily upset, the surplus metal being forced away fromthe elevated portions and tending to iill up the depressions. My plan ofconstruction effects considerable economy in cases where cast bars canadvantageously be used in the manufacture of commutators, since itaffords means by which the bars can be brought to accurate dimensionswithout machining.

In Fig. 2 .I have shown a type of roughening in which parallel groovesare formed along the sides of the bar. This result might be effected byscoring or rolling.

In Fig. 3 I have shown the face of the bar as provided with a number ofdiamond-shaped pits. The size of these is exaggerated for the purpose ofillustration, as, in fact, they might IOO be quite small While stillpromoting all the results aimed at by my invention. Thus the bars areheld from relative displacement by adhesion of the varnish, gum, orother suitable yielding material and by the Walls of the depressionsinto which it and the insulating material are squeezed.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. A commntator consisting of metal bars and insulating material, thebars having indentations on the lateral faces and being spaced apart byinsulation only so that the projecting parts of one bar do not overhangthose of another in a radial plane whereby movement of one bar relativeto another is prevented by the insulation.

2. Acommutator-barhavingitslateralfaces roughened to permit it to belocked against radial thrust.

3. A commutator composed of a plurality of bars having on their lateralfaces projections or roughnesses squeezed into firm engagement with aninsulating material between the successive bars.

4t. A commutator-bar having a roughened surface on its side Walls.

5. Acommutator-barofcastmetalprovided with indented roughened sides. i

G. A commutator having its several bars roughened and locked againstdisplacement by adhesive insulation over its entire surface.

7. A commutator having its several bars roughened on their sides andconnected together by adhesive insulation.

8. A commutator havingits several bars connected together by adhesivevarnish baked hard.

9. A coinlnutator having its several bars provided with roughened orindented surfaces connected by adhesive insulating material.

10. A commutator having its bars indented on adjacent sides, theindentations being connected by plane surfaces iinished to accurateprismatic dimensions.

1l. A commutator having its bars provided on their lateral faces withdepressions into which the insulating material between the bars mayexpand under heat and pressure.

12. A commutator having its several bars connected to the insulation byadhesive inaterial.

13. A commutator having its several bars connected to the insulation byadhesive varnish baked hard.

In Witness whereof I have hereunto set my hand this 8th day of May,1900.

WILLIAM L. R. EMMET.

Witnesses:

BENJAMIN B. HULL, EDWARD WILLIAMS, Jr.

